1. Field of the Invention
The present invention relates to surgical instruments known as trocars which are used in endoscopic surgery to penetrate an anatomical cavity of a patient to provide communication with the cavity during a surgical procedure. More particularly, the present invention relates to an improved tip for an obturator which is used in a trocar.
2. Description of the Prior Art
Endoscopic surgery is a significant method of performing surgical operations and has become the surgical procedure of choice due to its patient care advantages over “open surgery.” A particular type of endoscopic surgery is laparoscopic surgery. A significant advantage of laparoscopic surgery over open surgery is the decreased post-operative recovery time. In most instances, a patient is able to leave the hospital within hours after laparoscopic surgery has been performed, whereas with open surgery, a patient requires several days of hospital care to recover. Additionally, laparoscopic surgery achieves decreased incidents of post-operative abdominal adhesions, decreased post-operative pain, and enhanced cosmetic results.
Conventionally, a laparoscopic surgical procedure begins with the insufflation of the abdominal cavity with carbon dioxide. The introduction of this gas into the abdominal cavity lifts the abdominal wall away from the internal viscera. The abdominal wall is then pierced or penetrated with a device known as a trocar. A trocar includes a housing assembly, a cannula assembly attached to the housing assembly to form a bore through the trocar, and a piercing element called an obturator. The obturator slides through an access port formed on the upper end of the housing assembly and through the bore of the trocar. After insertion of the trocar through the abdominal wall of the patient, the obturator is removed by the surgeon while leaving the cannula protruding through the abdominal wall. The cannula may be fixed in place by using a fascia device, and laparoscopic instruments can then be inserted through the cannula to view internal organs and to perform surgical procedures.
Traditionally, the piercing tip of the obturator of a trocar has employed a sharp cutting blade to assist the surgeon in penetrating the abdominal wall. These obturators with cutting tips cut the tissue and muscle of the patient when inserted into the patient, and recovery time from the trauma of this cutting of tissue and muscle is necessary. Moreover, since the cutting tips are sharp, costly safety shield mechanisms are employed in trocars which operate to cover the obturator tip a short time after the obturator passes through the abdominal wall of the patient.
Certain trocars, for example, as disclosed in U.S. Pat. No. 5,817,601 to Goodwin, and U.S. Pat. No. 5,591,192 to Privitera have employed a pair of blunt-edged blades or tissue separators which are located on the tip of the trocar to facilitate the penetration or dissection of tissue.
Both of the trocar assemblies disclosed in U.S. Pat. No. 5,817,061 to Goodwin and U.S. Pat. No. 5,591,192 to Privitera are manufactured and sold by Ethicon Endo-Surgery, Inc. It is believed that trocars as described in the '061 and '192 patents have encountered significant problems since the tip of the obturator may be prone to failure. In particular, the tip of the trocars disclosed in the '061 and '192 patents is believed to have experienced incidents of snapping off during the insertion of the trocar. This failure may be attributable to the blunt shape of the tip and the forces to which the tip is subjected upon insertion.
An improvement over trocar car assemblies of the '061 and '192 patents is disclosed in U.S. patent application Ser. No. 09/994,321 filed Nov. 26, 2001 and assigned to the assignee of the present application. While the obuturator tip disclosed in the application is an improvement over the trocars of '061 and '192 patents, the trocar of the '321 application has the disadvantage of employing a piercing tip.